The present invention relates to a mining control system for adjusting the advance of the mining tools of a cutting machine for mining coal or other minerals and, more particularly, to the advance of the mining tools of a longwall mining machine of the type disclosed in U.S. Pat. No. 5,234,256.
A mining control system of this kind can experience problems with data transmission, concerning determined rock data, to the central command station, which controls the advance of the mining machine. In this connection, it is also necessary to take into account data transmission by radio, which is problematic in mining due to difficult transmitting conditions on the one hand and high safety requirements on the other. In particular, it is important for the decreased intensity of the radio signals caused by the distance of the mining machine from the receiving radio receiver not to be mistaken for a fluctuation of the measured quantity.
This risk of error is intensified by the difficult conditions in underground mining. This results again in hazards for the safe support of the longwall by incorrect readouts and wrong controls.
It is accordingly an object of the present invention to avoid these disadvantages and to equip a control system such that it operates free of wear and trouble and yet is robust and reliable.
The present invention solves the above and other problems by providing an improved control system for adjusting the advance of working tools of a mining machine, such as a mining machine of the type in which the working tools advance along and remove rock (e.g. coal) from a longwall. In accordance with the present invention, only the strongest of the radio signals that provide information about the rock being removed from the longwall is used for commanding the advance.
In accordance with one aspect of the present invention, the control system includes at least one detection device proximate the working tools of the mining machine. The detection device is operative for sensing characteristics of the rock to be removed from the longwall. The detection device is also operative for transmitting a radio signal that provides data representative of the characteristics of the rock to be removed. The control system also includes multiple radio receivers. Each of the radio receivers is operative for receiving the radio signal transmitted by the detection device. Additionally, the radio receivers are arranged in spaced relationship along the longwall such that the intensities of the radio signals received by the radio receivers vary from radio receiver to radio receiver. A comparator system of the control system is operative for comparing the intensities of the radio signals received by the radio receivers. The comparitor retransmits the one of those radio signals having the greatest intensity. A command station is operative for receiving the retransmitted radio signal. The command station generates command signals that are based upon the retransmitted radio signal, and the command signals control the advancing of the working tools.
In accordance with another aspect of the present invention, each of the radio receivers is associated with a respective comparitor that is operative for comparing the intensities of the radio signals received by the radio receivers. The comparitors are operative so that only the radio receiver receiving the most intense radio signal from the detection device retransmits data to the command station.